DebugPoint published a tutorial about how to upgrade to Ubuntu 21.04 from Ubuntu 20.10.

How to Upgrade to Ubuntu 21.04 from Ubuntu 20.10 (Groovy to Hirsute)

Here are the steps on how to upgrade your Ubuntu 21.04 from Ubuntu 20.10 (Groovy Gorilla to Hirsute Hippo). Ubuntu 21.04 Hirsute Hippo to be released this week on April 22, 2021. If you are running the prior short-term release – Ubuntu 20.10 Groovy Gorilla, then these are steps you need to follow to upgrade.

How to Upgrade to Ubuntu 21.04 from Ubuntu 20.10 (Groovy to Hirsute)